1. Field of Invention
The present invention relates to an exhaust gas aftertreatment method that regenerates a diesel particulate filter that traps particulate matters included in the exhaust gas and burns them out.
2. Description of Related Art
Reducing harmful matters is an important problem in a diesel automobile that generates a large amount of noxious exhaust gas. Particularly, it is necessary to reduce PM (particulate matters) caused by incomplete combustion of fuel.
A variety of techniques have been introduced to reduce the PM, and among them there is a DPF (diesel particulate filter) for trapping the PM in the exhaust gas and the temperature of DPF is raised up to a temperature higher than the ignition point thereof so that the PM will be eliminated.
The diesel particulate filter is smoothly regenerated in a condition that the exhaust gas temperature is high, like under high speed or high load, but the exhaust gas temperature must be forcibly raised to regenerate the DPF in a low load driving condition.
Meanwhile, a temperature of the DPF is raised during regeneration of the diesel particulate filter, if the engine enters into an idle condition in the mean time, a large amount of O2 suddenly flows into the diesel particulate filter to raise the inner temperature thereof, consequently there is a problem that the durability of the diesel particulate filter is worsen such that the DPF finally can be damaged.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.